On Mon, 18 Dec 2017 12:05:16 -0500
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> On Mon, 18 Dec 2017 17:12:15 +0900
> Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
>
> > Add SCTP ACK tracking trace event to trace the changes of SCTP
> > association state in response to incoming packets.
> > It is used for debugging SCTP congestion control algorithms,
> > and will replace sctp_probe module.
> >
> > Note that this event a bit tricky. Since this consists of 2
> > events (sctp_probe and sctp_probe_path) so you have to enable
> > both events as below.
> >
> > # cd /sys/kernel/debug/tracing
> > # echo 1 > events/sctp/sctp_probe/enable
> > # echo 1 > events/sctp/sctp_probe_path/enable
> >
> > Or, you can enable all the events under sctp.
> >
> > # echo 1 > events/sctp/enable
> >
> > Since sctp_probe_path event is always invoked from sctp_probe
> > event, you can not see any output if you only enable
> > sctp_probe_path.
>
> I have to ask, why did you do it this way?
>
>
> > +#include <trace/define_trace.h>
> > diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> > index 8f8ccded13e4..c5f92b2cc5c3 100644
> > --- a/net/sctp/sm_statefuns.c
> > +++ b/net/sctp/sm_statefuns.c
> > @@ -59,6 +59,9 @@
> > #include <net/sctp/sm.h>
> > #include <net/sctp/structs.h>
> >
> > +#define CREATE_TRACE_POINTS
> > +#include <trace/events/sctp.h>
> > +
> > static struct sctp_packet *sctp_abort_pkt_new(
> > struct net *net,
> > const struct sctp_endpoint *ep,
> > @@ -3219,6 +3222,8 @@ enum sctp_disposition sctp_sf_eat_sack_6_2(struct net *net,
> > struct sctp_sackhdr *sackh;
> > __u32 ctsn;
> >
> > + trace_sctp_probe(ep, asoc, chunk);
>
> What about doing this right after this probe:
>
> if (trace_sctp_probe_path_enabled()) {
> struct sctp_transport *sp;
>
> list_for_each_entry(sp, &asoc->peer.transpor_addr_list,
> transports) {
> trace_sctp_probe_path(sp, asoc);
> }
> }
>
> The "trace_sctp_probe_path_enabled()" is a static branch, which means
> it's a nop just like a tracepoint is, and will not add any overhead if
> the trace_sctp_probe_path is not enabled.
That's a good idea! I'll update to use it :)
Thank you,
>
> -- Steve
>
> > +
> > if (!sctp_vtag_verify(chunk, asoc))
> > return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
> >
>
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
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